How the CFCs become harmful to the Ozone layer? ♣ ♣ Normal reaction of the destruction of atmospheric O3:- ♣ Ozone, O3, is constantly being formed and broken up again in the high atmosphere by the action of ultraviolet light. ...See More Photo: How the CFCs become harmful to the Ozone layer? ♣ ♣ Normal reaction of the destruction of atmospheric O3:- ♣ Ozone, O3, is constantly being formed and broken up again in the high atmosphere by the action of ultraviolet light. ♣ Ordinary oxygen molecules absorb ultraviolet light and break into individual oxygen atoms. ♣ These have unpaired electrons, and are known as free radicals. They are very reactive. ♣ The oxygen radicals can then combine with ordinary oxygen molecules to make ozone. O2 + •O • = O3 ♣ Ozone can also be split up again into ordinary oxygen and an oxygen radical by absorbing ultraviolet light. O3 = O2 + •O • ♣ This formation and breaking up of ozone is going on all the time. ♣ Taken together, these reactions stop a lot of harmful ultraviolet radiation penetrating the atmosphere to reach the surface of the Earth. ♣ ♣ Effect of CFCs:- ♣ Chlorofluorocarbons (CFCs) were used extensively in aerosols and as refrigerants. ♣ Their slow breakdown in the atmosphere produces chlorine atoms i.e. chlorine free radicals. ♣ These catalyzed the destruction of the ozone. ♣ This happens in two stages. 1. In the first, the ozone is broken up and a new free radical is produced. Cl • + O3 = ClO • + O2 ♣ The chlorine radical catalyst is regenerated by a second reaction. 2. This can happen in two ways depending on whether the ClO • radical hits an ozone molecule or an oxygen radical. a. If it hits an oxygen radical which explained the production above, (•O • produced from the breakdown of O2 or O3 by UV light). ClO • + •O • = Cl • + O2 b. If it hits an ozone molecule: ClO • + O3 = Cl • + 2O2 ♣ Because the chlorine radical keeps on being regenerated, each one can destroy thousands of ozone molecules. ♣ Therefore this process is harmful to the O3 layer making it thinner and even piercing holes!
Posted on: Sat, 27 Jul 2013 11:53:14 +0000
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